The present invention relates to a subassembly for a vehicle seat and, more particularly, to a fitting for a motor vehicle seat.
WO 00/44582 discloses a subassembly which is designed as a fitting and is provided as an inclination adjuster for the backrest of a vehicle seat. Frequent changes in the inclination of the backrest result in a certain amount of wear in the long term.
One aspect of the present invention is the provision of an improved subassembly for a vehicle seat, in particular a fitting for a motor vehicle seat, having a first component and a second component which can move relative to the first component. By way of regions which are assigned to the first component, the second component is mounted, guided and/or supported with respect to the first component or interacts therewith in another manner. The first component is at least partially hardened.
By virtue of the first component (and preferably also the second component) being at least partially hardened, the wear behavior can be significantly improved and, by increasing the fatigue strength, the service life of the subassembly can be significantly increased. The clearance which is present is not enlarged, so that malfunctions of the fitting are avoided. In addition, a relatively high surface pressure is possible in the hardened regions, which increases the range of use of the fitting according to the invention.
In order to keep the increased outlay and production low in terms of costs and in order not to change the static and dynamic behavior of the component to a great extent, the first component is preferably hardened only in those regions which interact with components of the fitting which can move relative to the first component, for example the bearing and/or the guide and/or other supports, and, in particular, is preferably only hardened locally, i.e. on the bearing surfaces, guide surfaces, tooth surfaces and other supporting surfaces, and is otherwise unhardened. The reduction in the wear does not affect the geometrical qualities of these supporting surfaces.
In a particularly preferred embodiment, the hardened regions are specifically hardened in the boundary layer by means of a laser. In comparison with case hardening or induction hardening, this method has the advantage that a better dimensional stability can be obtained, that specific hardening with a defined hardening zone geometry can take place in certain regions, and that only a small distortion of the component occurs after cooling. Owing to the low drawing-in of heat, which is caused by the method, after the hardening process, the component can be immediately further processed. A quenching medium is not required, since automatic quenching takes place, i.e. the heat, which is introduced, is dissipated into the cold base material predominantly by thermal conduction. In addition, a more cost-effective use within a fully automatic installation system is possible.